Texture filtering

Texture filtering refers to the methods used to smooth the textures of a 3D model. Every home console after the Nintendo 64 is able to do it, including every modern PC and Android device. This makes it useful in emulation, where it can be applied to emulators for consoles that did not originally have it through various emulators that support it.

This article is about smoothing techniques that may be present even on original hardware. For the process of replacing textures to improve their visual fidelity or other aesthetic reasons, see Texture Packs.

Console	Texture Filtering	Types of filtering
Super Nintendo	✗
3DO	✗	?
Atari Jaguar	✗
Sega Saturn	✗
PlayStation	✗
Nintendo 64	✓	Three-sample
Sega Dreamcast	✓	Bilinear, trilinear, anisotropic
PlayStation 2	✓	Bilinear, trilinear, Anisotropic
GameCube	✓	Bilinear, trilinear, anisotropic
Xbox	✓	Bilinear, trilinear, anisotropic
Nintendo DS	✗	?
PlayStation Portable	✓	Bilinear, trilinear
Wii	✓	Bilinear, trilinear, anisotropic

Texture Filtering Algorithms

These methods determine how a texture is sampled and displayed on a 3D model. They are generally native to original hardware or very common in all 3D emulators.

Filtering type	What it does	Pros	Cons
Nearest neighbor	This scaling method assigns each output pixel the color of the single closest pixel in the original image (no averaging or blending). When enlarging an image, each source pixel is effectively “copied” into a block of identical pixels (e.g., 2× scaling turns 1 pixel into a 2×2 block). This preserves hard edges and a crisp, blocky appearance.	Fast and computationally cheap (minimal GPU cost). Preserves sharp pixel-art style with practically no blur or smoothing when using with integer scaling.	If the output is not a perfect multiple (e.g., integer scaling 240p to 1080p), and instead using non-integer scaling: it causes uneven pixel sizes, leading to distortion, shimmer, or wobble artifacts during movement. Text and fine details can look distorted or "warped" on modern displays if the scaling isn't perfectly aligned. To avoid distortion, users often must use "Integer Scaling", which usually results in black bars on the top/bottom or sides of the screen on modern displays.
Bilinear (Smooth)	This linear filtering method uses color data from the pixels in a nearest-neighbor texture, and combines multiple bits of color data in order to replace some of the pixels with an averaged-out version of the colors, so that the colors gradually switch rather than jump to a new color.	Looks better than nearest neighbor for 3D games. It's the least system-intensive form of texture filtering/scaling.	At low resolutions, 2D games tend to become very blurry. This is especially noticeable in 2D games, and low res 3D games. If you have the hardware to do so, look into more complex filtering methods to preserve clarity.
Bilinear (Sharp) (Bilinear with Prescale)	A technique that first scales the image using Nearest Neighbor to the largest possible integer size, then uses Bilinear filtering for the final "small" stretch to fill the screen.	Eliminated "pixel shimmer" or "wobble" during scrolling. Keeps pixels looking sharp and square while filling the entire screen (even at non-integer scales).	Requires a shader or specific support from emulator (like RetroArch or PCSX2). Technically a tiny bit of blur on the very edges of pixels compared to pure Nearest Neighbor.
Trilinear	This linear filtering method does the same thing as bilinear filtering, but additionally interpolates between mipmaps (downscaled versions of the texture used for far away objects), thereby preventing mipmap banding (harsh transitions between mipmap levels).	Looks better than bilinear filtering for 3D games.	As with bilinear, low-resolution games will more than likely appear overly blurry using this method.
Spline36	A high-order mathematical interpolation method. Unlike Bilinear, which only looks at the immediate surrounding pixels, Spline36 uses a larger 6x6 grid of pixels to calculate new color values.	Sharper and more accurate than Bilinear/Trilinear. Reduces "aliasing" (stair-stepping) on textures compared to simpler filters. Very computationally efficient on modern hardware.	Can occasionally produce "ringing" artifacts (faint halos around high-contrast edges). While sharper than Bilinear, it still looks like a "blurrier" upscale compared to dedicated pixel scalers like xBRZ.

Texture Scaling Algorithms

For smoothing shaders, see Shaders, presets and filters#Smoothing Shaders.

These are enhancement algorithms (often called "upscalers") used by emulators to increase the resolution of textures to look better on modern displays.

Scaling Algorithm	What it does	Pros	Cons
HQx	A texture scaling algorithm. Scales up a nearest-neighbor version of the texture and fills in the gaps with copies of the pixels next to said gaps.	While it is inherently destructive, some games (eg. Yoshi's Island) may benefit from this filter, as it preserves the cartoony look.	Artifacts are common. Curves and slopes that aren't 45° look jagged compared to everything else. The finer details of the textures/sprites might be obscured by bad edge detection. Posterization is very common. There are deposterization filters in some emulators (e.g. PPSSPP) that can aid this, however. Worse at some things that xBR excels at.
2xSaI	A texture scaling algorithm. Scales the texture and fills edges in with a mixture of pixels taken from the source and randomly-guessed colors.	Less system-intensive than HQx and xBR. Adequate if it's the best option available (e.g. in Pete's OpenGL2 plugin for PSX emulators).	Edge detection is horrible. Artifacts are common. Posterization is very common. Archaic. The alternatives are much better.
xBR	A modified version of HQx. It detects edges better, which works better for curved lines, or for slopes that are greater than/less than 45 degrees.	Looks great for many 2D games. Edge detection is improved over HQx. This gives textures smoother curves and slopes, as well as fewer artifacts. 3D games look great with it as well.	Posterization is common. There are deposterization filters in some emulators (e.g. PPSSPP) that can aid this, however. The finer details of the textures/sprites might be obscured by bad edge detection. Worse at some things that HQx excels at.
xBRZ	A modified version of xBR, which is very similar except it's better at scaling up smaller features consisting of <10 pixels.	Looks great for many 2D games. Detects small features that get messed up by HQx and xBR. 3D games look great with it as well.	Posterization is common. There are deposterization filters in some emulators (e.g. PPSSPP) that can aid this, however. Worse at some things the other scalers excel at.
MMPX	A texture scaling algorithm. Provides a nearly unfiltered, "Retro Plus" pixel art aesthetic with better handling of rounded and diagonal edges, similar to that found in many indie games.	Has better handling of diagonals and curves than other scalers. Does not alter the art style to look cartoonish or posterized the way HQx and xBR do. Looks great for both 2D and 3D games designed with pixelated graphics in mind.	Looks pixelated, highlighting the low resolution. Textures scaled horizontally and vertically at unequal levels can produce awkward results. Resolution hacks may be able to fix this in some instances.
NNEDI3	A neural network-based "edge-directed" interpolator. It uses a pre-trained model to predict what missing pixels should look like based on existing edges and structures.	Exceptional at preserving sharp edges without the "oil painting" look of xBRZ. Virtually eliminates jagged edges (aliasing) on 2D elements and UI. Considered one of the highest-quality "clean" upscalers available.	Extremely hardware intensive compared to every other filter on this list; requires a capable GPU. Can sometimes introduce small "wobbles" or artifacts in very complex, noisy textures where the AI misidentifies an edge.

Emulator Specific

These are specific options found in emulators like PPSSPP that modify or combine the methods listed above to achieve better results. PPSSPP has a scaling option known as "Hybrid." There's also an option called "Deposterize." Posterization, meaning a sharp contrast in hue from one pixel to another (very common in low-quality gifs) has been a problem plaguing texture scaling algorithms for quite some time. Durante's filter switches between xBR and bilinear/bicubic filtering depending on the texture information. On top of this, the "Deposterize" option tackles posterization edges in compressed textures, allowing for a smooth gradient rather than a sharp transition. Although it's not perfect (a perfect scaler sadly isn't possible with today's computing power) it's still great and it's recommended to use for PPSSPP if you have the specs.

Feature	What it does	Pros	Cons
Hybrid / Hybrid + Bicubic	A scaling method that switches between xBR and bilinear/bicubic filtering depending on the texture information. It attempts to detect which parts of a texture need sharp edge enhancement and which are smooth gradients.	The "best of both worlds": preserves sharp edges where needed while keeping smooth areas (like skies) from looking blocky or "posterized." Generally considered the "Gold Standard" for a balanced look in PPSSPP if the hardware can handle it.	Highly system-intensive. While it aims for a perfect balance, a perfect scaler isn't possible with today's computing power, so some textures may still look slightly inconsistent.
Deposterize	A filter that tackles "posterization" (sharp, ugly jumps in color hue common in compressed textures) by smoothing out the transitions into a natural gradient.	Allows for a smooth gradient rather than a sharp, blocky transition in colors. Greatly reduces the "oil painting" artifacts that often plague other texture scaling algorithms. Highly recommended for use in PPSSPP if you have the specs to support it.	Can occasionally "wash out" textures where sharp color transitions were an intentional part of the art style. Adds extra load to the GPU when combined with high-level scalers.

Images

PSP game with linear filtering
PSP game with nearest neighbor
PSP game with 3xBR texture scaling

N64 game at native internal resolution (using SoftGraphic plugin)
N64 game upscaled with bilinear filtering (using Glide64 plugin)
N64 game upscaled with nearest neighbor (using Glide64 plugin)

SNES game with nearest neighbor
SNES game with linear filtering

SNES game with nearest neighbor
SNES game with HQ4x texture scaling
SNES game with 5xBR texture scaling

Texture filtering hacks

Some emulators features better texture filtering: enhancement option for providing better texture filtering methods comparing the original hardware had. See;

sections.